1. Field of the Invention
The present invention relates to an artificial chamber that is used to support and pressurize a donor cornea to facilitate the removal of a corneal graft.
2. Background Information
There have been developed various techniques to correct the vision of a patient. For example, there is a medical procedure that varies the curvature of a cornea using a laser. This technique is commonly referred to as Las in situ Keratomileusis (LASIK).
A LASIK procedure is performed by initially cutting a flap in the cornea to expose the stroma layer of the eye. A laser beam is then directed onto the stroma to ablate corneal tissue. After ablation the flap is placed back onto the stroma. The result is a variation in the refractive characteristics of the eye.
The flap may become severed from the cornea either during or after the procedure. This may require obtaining another flap from a donor eye that must then be attached to the patient""s cornea. To create a replicant corneal flap the donor corneal must be pressurized to create the proper radius of curvature. Therefore, to create a flap the donor cornea must not only be secured but also pressurized.
U.S. Pat. No. 6,045,563 issued to Duprat and assigned to Moria SA (xe2x80x9cMoriaxe2x80x9d), discloses an artificial chamber that can be used to support and pressurize a cornea to extract a corneal graft. The Moria chamber includes a clamping cap that can be removed from a chamber stand to expose an internal stem. The donor cornea can be placed onto a pedestal portion of the internal stem. The clamping cap is then reattached to the stand.
An operator rotates a thumb wheel that moves the stem in an upward direction until the cornea engages the bottom surface of the clamping cap. The cornea is pressurized with air that flows through a center channel of the stem. A portion of the pressurized donor cornea extends through an opening in the clamping cap. A keratome can be attached to the cap and actuated to slice a graft from the cornea.
The Moria artificial chamber requires the operator to rotate the wheel until the cornea is secured to the clamping cap. This manual actuation may result in a deficient, or an excessive, clamping force on the cornea. It is desirable to have a clamping force that is the same for each procedure. The Moria patent discloses a second pneumatically actuated embodiment that would provide a repeatable clamping force, but the pressure required to move the stem may be less, or more, than the desired clamping force exerted onto the cornea. It would be desirable to provide an artificial chamber that can provide a repeatable desired clamping force on a cornea during a grafting procedure.
One embodiment of the present invention is an artificial chamber that can be used to support and pressurize a cornea to extract a corneal graft. The artificial chamber may include a stem that is attached to a stand. The stem is adapted to support and pressurize a cornea. The chamber may further have an outer sleeve and a cap that can move relative to the stem. The sleeve and cap can be moved by an actuator to secure the cornea.